1. Кіріспе
Custom metal castings are essential components in modern manufacturing, enabling engineers to transform molten metal into complex, application-specific parts that would be difficult or uneconomical to produce by machining alone.
From aerospace brackets and automotive housings to pump casings and medical devices, these castings provide the flexibility to tailor geometry, материал, and mechanical properties to precise requirements.
2. What Are Custom Metal Castings?
Custom metal castings are purpose-designed metal components created by pouring molten metal into a mold shaped to the part’s geometry, allowing it to solidify, and then finishing it to meet specific dimensional and mechanical requirements.
Unlike standard or catalog castings, custom castings are tailored to the unique needs of a project, whether that involves complex geometries, specialized alloys, Қатаң төзімділіктер, or specific mechanical properties.
These castings can range from кішкене, precision investment-cast parts weighing just a few grams for aerospace or medical applications, қарай large sand-cast housings and industrial components weighing hundreds of kilograms.
The “custom” aspect emphasizes the integration of design flexibility, Материалдық таңдау, and process optimization to satisfy unique performance, төзімділік, and operational requirements.
Key characteristics of custom metal castings include:
- Tailored geometry: internal cavities, undercuts, and complex shapes that reduce assembly and welding.
- Material versatility: broad selection of alloys, including aluminum, болат, үтік, мыс, and nickel-based materials.
- Масштабтау: options for low-volume prototypes to high-volume production runs.
- Performance-oriented design: Механикалық беріктік, Коррозияға төзімділік, thermal properties, and fatigue life can all be engineered into the part.
By leveraging these characteristics, custom metal castings enable нәтижелі, орнықты, and high-performance solutions across industries ranging from automotive and aerospace to energy, теңіз, және медициналық құрылғылар.
3. Key Casting Processes for Custom Metal Castings
Selecting the right casting process is essential to achieving the desired geometry, Механикалық қасиеттері, Бетті аяқтау, және экономикалық тиімділік.
Different processes are optimized for part size, complexity, дыбыс, and alloy.
Құмның құюы — The Workhorse of Customization
Өңдеу: Molten metal is poured into a sand mold formed around a pattern. The sand mold may consist of green sand (clay and sand) or chemically bonded sand for higher precision.
After the metal solidifies, the mold is broken away, and the casting is removed. Runners, risers, and cores may be used to ensure complete filling and dimensional integrity.
Артықшылықтары:
- Low tooling cost and flexible mold sizes, ideal for prototyping and small-batch production
- Suitable for large or heavy parts (up to several tons)
- Compatible with nearly all alloys, including ferrous and non-ferrous metals
- Relatively quick mold preparation compared with complex investment or die casting
Шектеулер:
- Coarser surface finish (Ra ~6–12 µm)
- Dimensional tolerances are relatively loose (±0.5–3 mm)
- Requires post-casting machining for critical surfaces
- Porosity and inclusions can occur if gating and risers are not optimized
Қолданбалар: Сорғы корпустары, Қозғалтқыш блоктары, large industrial machinery components, Клапанның денелері
Practical tip: Using chemically bonded sand or shell molding as an upgrade can improve surface finish and reduce dimensional variation.
Инвестициялық құю (Lost-Wax Casting) — Precision for Complexity
Өңдеу: A wax pattern is coated with a ceramic shell; after curing, the wax is melted out, leaving a cavity.
Molten metal is poured into this cavity under gravity or vacuum, then allowed to solidify.
The ceramic shell is broken off to reveal the final casting. This process can produce highly intricate shapes with thin sections and detailed features.
Артықшылықтары:
- Superior surface finish (Ra 0.4–1.6 µm)
- Tight tolerances (±0.1–0.5 mm), ideal for high-precision parts
- Capable of producing thin walls and complex internal geometries
- Minimal need for post-machining for non-critical surfaces
Шектеулер:
- Higher per-part cost than sand casting
- Tooling for wax patterns can be expensive and time-consuming
- Long lead times for tooling and batch production
Қолданбалар: Aerospace brackets, Турбина пышақтары, Медициналық импланттар, precision instrument components
Practical tip: Use vacuum or centrifugal casting variants to further reduce porosity and improve surface quality for critical aerospace or medical components.
Кастинг өледі — High-Volume Customization
Өңдеу: Балқытылған металл (typically aluminium, мырыш, or magnesium) is injected under high pressure into a steel die.
The die is water-cooled to control solidification, and parts are ejected automatically. This process is highly repeatable and suitable for mass production.
Артықшылықтары:
- Тамаша өлшемді дәлдік (±0.05–0.2 mm)
- Smooth surface finish (Ra 0.8–3.2 µm)
- Fast production cycles and high repeatability
- Thin-wall sections are possible, reducing part weight and material consumption
Шектеулер:
- High initial tooling costs ($10,000–$250,000+)
- Limited to low-melting-point alloys
- Porosity can occur if injection speed or die temperature is not optimized
- Limited geometric complexity compared to investment casting
Қолданбалар: Automotive housings, Тұтынушы электроника, Беріліс компоненттері, precision machinery covers
Practical tip: Die-cast parts often require secondary machining or heat treatment to achieve critical tolerances and mechanical properties, especially for aluminium alloys.
Қабықшаны құю
Өңдеу: A resin-coated sand shell is applied around a heated pattern multiple times to build up the mold wall thickness. The pattern is removed, and molten metal is poured into the shell.
This process produces parts with better surface finish and dimensional accuracy than green sand casting.
Артықшылықтары:
- Improved surface finish and tolerance compared with traditional sand casting
- Ideal for small-to-medium-sized parts
- Good for alloys such as steel, үтік, және алюминий
Шектеулер:
- Higher tooling cost than green sand
- Limited part size due to shell fragility
- Mold preparation is more labor-intensive
Қолданбалар: Gearbox housings, small pump components, Клапанның денелері
Practical tip: Use ceramic coating with multiple layers to achieve tighter tolerances and reduce metal penetration in high-temperature alloys.
Lost-Foam Casting
Өңдеу: A foam pattern is created to match the final part geometry. The foam is coated with refractory material and placed in unbonded sand.
Molten metal vaporizes the foam, filling the cavity in its place. This method allows for complex shapes without cores.
Артықшылықтары:
- Allows intricate geometries, including undercuts and internal cavities
- Smooth surface finish, minimal machining for non-critical areas
- Reduced assembly needs due to complex single-piece designs
Шектеулер:
- Foam pattern fabrication requires precision
- Limited to alloys with suitable pouring temperatures
- Risk of casting defects if foam decomposition is incomplete
Қолданбалар: Автомобиль қозғалтқышының блоктары, complex industrial parts, marine components
Practical tip: Ensure proper venting and foam density control to minimize shrinkage and porosity.
Gravity Casting
Өңдеу: Molten metal fills a mold solely under the force of gravity. Often used for aluminum, жез, or other non-ferrous alloys, gravity casting can produce simple to moderately complex parts efficiently.
Артықшылықтары:
- Low-cost and simple setup
- Suitable for medium-size, moderate-precision parts
- Minimal specialized equipment required
Шектеулер:
- Surface finish and tolerances are coarser than pressure-assisted processes
- Less suitable for thin-wall sections or highly intricate geometries
Қолданбалар: Brackets, корпустар, decorative components
Practical tip: Use controlled mold preheating and gating design to reduce turbulence and shrinkage defects.
Centrifugal Casting — Custom Cylindrical Parts
Өңдеу: Molten metal is poured into a spinning mold. Centrifugal force pushes the metal against the mold walls, resulting in dense, uniform cylindrical castings.
Артықшылықтары:
- Produces dense, defect-free cylindrical parts
- Excellent directional solidification and mechanical properties
- Reduced porosity and inclusions in critical sections
Шектеулер:
- Restricted to rotationally symmetric geometries
- Requires specialized spinning equipment and tooling
Қолданбалар: Бағдарлау, bushings, құбырлар, rollers, cylindrical industrial components
Practical tip: Adjust spin speed and mold temperature to optimize microstructure and mechanical properties for high-stress applications.
Summary Table of Processes
| Өңдеу | Part Size | Бетті аяқтау | Tolerance | Өндіріс көлемі | Typical Alloys | Қолданбалар |
| Құмның құюы | Large | Ra 6–12 µm | ±0.5–3 mm | Low–Medium | Болат, Үтік, Алюминий | Сорғы корпустары, Қозғалтқыш блоктары |
| Инвестициялық құю | Small–Medium | Ra 0.4–1.6 µm | ±0.1–0.5 mm | Low–Medium | Болат, Алюминий, Nickel alloys | Aerospace brackets, Турбина пышақтары |
| Кастинг өледі | Small–Medium | Ra 0.8–3.2 µm | ±0.05–0.2 mm | Биік | Алюминий, Мырыш, Магний | Automotive parts, consumer housings |
| Shell Mold | Small–Medium | Ra 3–6 µm | ±0.2–1 mm | Амал | Болат, Үтік, Алюминий | Gearbox housings, pump parts |
| Lost-Foam | Амал | Ra 2–6 µm | ±0.2–1 mm | Амал | Алюминий, Үтік | Автомобиль, industrial parts |
| Gravity | Амал | Ra 6–12 µm | ±0.5–2 mm | Аласа | Алюминий, Жез | Brackets, корпустар |
| Centrifugal | Medium–Large | Ra 3–8 µm | ±0.2–1 mm | Амал | Болат, Copper alloys | Bushings, құбырлар, бағдарлау |
4. Material Selection for Custom Metal Castings
Selecting the appropriate material is one of the most critical decisions in custom metal casting.
The choice influences Механикалық қасиеттері, Коррозияға төзімділік, thermal performance, Айналымдылық, құны, and suitability for the intended casting process.
Common Alloys for Custom Metal Castings
| Alloy Family | Typical Density (g / cm³) | Балқу диапазоны (° °) | Typical Tensile Strength (МПа) | Негізгі артықшылықтар | Жалпы қосымшалар |
| Алюминий Қорытпалар (A356, ADC12) | 2.6–2.8 | 560–660 | 150–320 | Жайғақ, corrosion-resistant, good thermal conductivity | Automotive parts, aerospace housings, Жылу алмастырғыштар |
| Сұр шойын | 6.9–7.3 | 1150–1250 | 150–350 | Excellent vibration damping, cost-effective | Қозғалтқыш блоктары, Сорғы қалталары, Клапанның денелері |
| Ductile (Nodular) Үтік | 7.0–7.3 | ~1150–1250 | 350-700 | Жоғары созылу күші, әсерге қарсы тұрақтылық | Берікек, heavy machinery components, pressure housings |
| Көміртегі & Low-Alloy Steels | 7.85 | 1425-1540 | 400–800 | Жоғары беріктігі, дәнекернді | Құрылымдық компоненттер, pressure parts |
| Тот баспайтын болаттар (304, 316, Cf8m) | 7.9–8.0 | 1375–1400+ | 450–800 | Тамаша коррозияға төзімділік, hygienic | Food processing, теңіз, Химиялық жабдықтар |
| Мыс Қорытпалар (Қола, Жез) | 8.4–8.9 | 900–1050 | 200-500 | Corrosion resistance, Айналымдылық, thermal/electrical conductivity | Бағдарлау, marine components, electrical fittings |
| Nickel-Based Alloys (Жұқпалы, Гастеля) | 8.1–8.9 | 1300–1400+ | 500–1200 | High-temperature strength, Коррозияға төзімділік | Turbines, chemical reactors, aerospace critical parts |
5. Design for Manufacture (DFM) for Castings
Design for Manufacture (DFM) ensures that custom metal castings are dimensionally accurate, structurally sound, and cost-effective while minimizing defects and post-processing requirements.
The key aspects can be summarized and compared in a table for clarity.
Key DFM Guidelines
| Белгі | Recommendations | Типтік ауқым / ЕСталдар | Мақсат / Пайда келтіру |
| Қабырғалы қалыңдығы | Maintain uniform thickness; gradual transitions between thick and thin areas | Құмның құюы: 6–40 mm; Investment: 1–10 mm; Кастинг өледі: 1–5 mm | Prevents shrinkage, hot spots, and internal stresses |
| Draft Angle | Provide draft for mold removal | Құм & Investment: 1–3°; Кастинг өледі: 0.5–2° | Minimizes surface defects, tool wear, and ejection issues |
| Fillets & Radii | Avoid sharp corners; radius ≥0.25–0.5× wall thickness | Depends on wall thickness | Reduces stress concentration and improves metal flow |
| Ribs & Stiffeners | Add ribs to increase rigidity without thickening walls | Rib thickness ≤0.6× wall thickness | Enhances strength while controlling weight and material use |
| Bosses & Core Features | Ensure adequate fillets and draft; stable core prints | Varies by part geometry | Prevents distortion, breakage, and filling defects |
| Parting Lines | Align along low-stress areas; minimize undercuts | Indicated in CAD models | Facilitates mold removal, reduces machining, and improves surface finish |
| Сүйинг & Risers | Smooth bottom-up flow; risers for directional solidification; use chills if necessary | Design optimized via simulation | Reduces porosity, кішірейту, and turbulence defects |
| Бетті аяқтау | Define finish according to casting process | Құм: Ra 6–12 µm; Investment: Ra 0.4–1.6 µm; Die: Ra 0.8–3.2 µm | Determines post-machining requirements and functional aesthetics |
| Machining Allowance | Include extra material for finishing critical surfaces | 1–6 mm depending on process | Ensures final dimensions meet tolerance requirements |
| Tolerances | Define according to casting type and criticality | Құм: ±0.5–3 mm; Investment: ±0.1–0.5 mm; Die: ±0.05–0.2 mm | Ensures functional fit and reduces secondary processing |
6. Post-Casting Operations and Finishing
After a custom metal casting solidifies and is removed from the mold, post-casting operations are crucial to achieve the final part quality, өлшемді дәлдік, and functional performance.
These operations include heat treatment, өңдеу, Бетті әрлеу, жабындар, and assembly-ready processes.
Термиялық өңдеу
Heat treatment adjusts the Механикалық қасиеттері, stress levels, and microstructure of the casting. Common methods include:
| Method | Мақсат | Typical Materials | Негізгі әсерлер |
| Ақша салу | Relieves residual stresses, improves ductility | Carbon steel, Тот баспайтын болат, алюминий | Reduces hardness, Техникалық жұмыстарды жақсартады |
| Қалыпқа келтіру | Refines grain structure, improves toughness | Carbon and alloy steels | Uniform microstructure, enhanced tensile strength |
| Сөндіру & Тымбитора | High strength with controlled hardness | Легірленген болаттар, tool steels | Increases yield strength, қаттылық, және қарсылық киіңіз |
| Стресті жеңілдету | Reduces distortion from machining or welding | All steels, Ішкі үтік | Minimizes cracking and warping during machining |
Өңдеу
- Өңдеу is performed to achieve critical dimensions, Қатаң төзімділіктер, and smooth surfaces where required.
- Techniques include milling, бұру, бұрғылау, іш пыстыратын, және ұнтақтау.
- Machining allowances should be considered in DFM (typically 1–6 mm depending on casting process and criticality).
Practical tip: Use CNC machining for complex features, and sequence operations to minimize residual stresses.
Surface Treatment and Finishing
Surface treatments improve көрінос, Коррозияға төзімділік, and wear properties:
| Treatment | Мақсат | Typical Materials | ЕСталдар |
| Shot Blasting / Sand Blasting | Remove sand or scale, improve surface texture | Болат, үтік, алюминий | Prepares surface for coating or painting |
| Жылтырату / Buffing | Achieve smooth or mirror finish | Тот баспайтын болат, алюминий, жез | Required for aesthetic or hygienic applications |
| Ұнтақтау / Lapping | Achieve tight flatness or surface tolerance | Болат, үтік, алюминий | Used on sealing faces or mating surfaces |
| Жабындар / Plating | Corrosion resistance, wear protection, эстетика | Мырыш, никель, эпоксий, Ptfe | Electroplating or powder coating common; thickness 10–50 µm typical |
7. Quality Control and Testing for Custom Metal Castings
Dimensional inspection
- См, laser scanning and optical inspection verify geometry against CAD and tolerances.
Non-destructive testing (NDT)
- Рентгенографиялық (Рентген): detect internal porosity and inclusions.
- Ultrasonic testing (У): thickness and planar defects.
- Magnetic particle (М.ғ.д.) & бояғыш (PT): surface and near-surface crack detection.
Mechanical & metallurgical testing
- Созық, қаттылық, impact tests on specimens or coupons.
- Химиялық талдау (OES) for alloy verification.
- Microstructure checks for grain size, segregation or unwanted phases.
Common defects and mitigation
- Кеуелік: degassing, filtration, optimized gating.
- Shrinkage cavities: better risering and directional solidification.
- Cold shuts / misruns: higher pouring temperature, gating redesign.
- Inclusions: melt cleanliness, charge material control, filtration.
8. The Value of Custom Metal Castings
Custom metal castings offer unique advantages that make them indispensable across industries where performance, complexity, and cost-efficiency are critical.
Дизайн икемділігі
Custom castings allow complex geometries that would be difficult or costly to achieve with machining or fabrication alone.
Features such as internal cavities, Жіңішке қабырғалар, undercuts, ribs, and integrated bosses can be incorporated directly into the casting, reducing the need for additional assembly or welding.
This not only simplifies the supply chain but also enhances part integrity and reliability.
Material Optimization
A wide range of alloys—including aluminum, Ішкі үтік, Тот баспайтын болат, мыс, and nickel-based alloys—can be selected to meet механикалық, thermal, and corrosion requirements.
Designers can choose materials that provide the ideal balance of strength, weight, төзімділік, and resistance to specific environmental conditions.
Шығындар тиімділігі
For medium-to-large parts or complex shapes, custom castings often reduce material waste and machining time compared with subtractive manufacturing.
Part consolidation—combining multiple components into a single casting—further cuts assembly costs and minimizes potential leak paths, especially in fluid-handling systems.
Performance and Reliability
Custom castings can be engineered for specific operational conditions, such as high temperature, Жоғары қысым, or corrosive environments.
Properly designed and manufactured castings ensure consistent mechanical performance, high fatigue life, and reduced risk of failure, making them suitable for safety-critical applications.
Scalability and Versatility
Custom castings can be produced as prototypes for validation or in high-volume production.
Processes like sand casting allow rapid prototyping for large parts, while investment and die casting support high-precision or high-volume needs.
This scalability enables manufacturers to match production methods to project requirements efficiently.
9. Challenges in Custom Metal Casting
Custom metal casting is a versatile and cost-effective manufacturing method, but it comes with inherent challenges.
| Шақыру | Cause | Mitigation |
| Өлшемді дәлдік | Shrinkage, warping, Жылу кеңеюі | Simulation, DFM design, machining allowance |
| Internal Defects (Кеуелік, Shrinkage, Cold Shuts) | Turbulent flow, poor gating/venting, alloy issues | Optimized gating, risers, mold venting, NDT inspection |
| Материалдық шектеулер | High melting point alloys, low fluidity | Select compatible alloys, advanced process control |
| Бетті аяқтау & Өңдеу | Rough molds, thin-wall sections | Shot blasting, жылтырату, design optimization |
| Құралдар & Құны | Complex molds, high-precision cores | Prototyping, batch optimization, cost-benefit analysis |
| Сапаны бақылау | Process variability, operator skill | Standardized QC, in-process monitoring, NDT |
| Safety & Environment | High-temperature metals, chemical binders | PPE, желдеткіш, eco-friendly materials |
10. Industrial Applications of Custom Metal Castings
Custom metal castings are widely used across industries due to their ә маяғы, күш, and ability to produce complex geometries.
Their applications span from heavy machinery to precision components in high-tech sectors.
Автомобиль өнеркәсібі
- Қозғалтқыш компоненттері: Cylinder heads, Қозғалтқыш блоктары, exhaust manifolds
- Transmission & drivetrain parts: Gear housings, differential cases, Тежегіш компоненттері
- Жамандық: Lightweight alloys (aluminium, магний) reduce vehicle weight, Жанармай тиімділігін арттыру
Аэроғарыш және қорғаныс
- Components: Turbine blades, structural brackets, landing gear housings, precision fittings
- Requirements: Жоғары күш-салмаққа қатынасы, Шаршауға төзімділік, Қатаң төзімділіктер
- Материалдар: Алюминий, титан, nickel-based superalloys
- Жамандық: Complex shapes and near-net designs reduce assembly and machining
Energy and Power Generation
- Components: Pump casings, Клапанның денелері, turbine housings, generator parts
- Requirements: Corrosion resistance, high-temperature performance, mechanical reliability
- Материалдар: Тот баспайтын болат, Көміртекті болат, Ішкі үтік
- Жамандық: Durable castings withstand thermal cycling and high-pressure environments
Өнеркәсіптік техника
- Components: Беріліс қораптары, rollers, жақтаулар, machine bases, bearing housings
- Requirements: Жоғары беріктігі, vibration damping, тозуға төзімділік
- Материалдар: Gray iron, Ішкі үтік, легірленген болаттар
- Жамандық: Large, heavy-duty parts manufactured efficiently with minimal machining
Marine and Offshore
- Components: Propeller shafts, Сорғы корпустары, Клапанның денелері, offshore platform fittings
- Requirements: Corrosion resistance, Механикалық беріктік, seawater compatibility
- Материалдар: Қола, Тот баспайтын болат, duplex stainless steel
- Жамандық: Long-lasting components with reduced maintenance in harsh environments
Medical and Precision Instruments
- Components: Surgical tools, импланттар, dental frameworks, precision housings
- Requirements: Биокомпания, high dimensional accuracy, smooth surface finish
- Материалдар: Тот баспайтын болат, cobalt-chrome alloys, титан
- Жамандық: Complex geometries achievable with investment casting; minimal post-processing
11. Innovations and Future Trends in Custom Metal Casting
The industry is evolving rapidly, driven by digitalization, sustainability, and additive manufacturing (Боламын):
Қоспа өндірісі (Боламын) Integration
- 3D-Printed Molds/Patterns: Binder jetting prints sand molds (ExOne) or wax patterns (Desktop Metal) in 1–3 days, cutting tooling lead time by 70%.
Мысалы, a custom sand-cast aluminum bracket prototype takes 2 days with 3D molds (қарсы және. 2 weeks with wooden patterns). - Direct Metal AM for Small Parts: DMLS (Direct Metal Laser Sintering) produces fully dense titanium implants with ±0.05 mm tolerance—eliminating casting for one-off parts.
Digitalization and Smart Casting
- Digital Twins: Virtual replicas of casting processes (MAGMASOFT, AnyCasting) simulate mold filling and solidification, optimizing parameters in real time. This reduces defect rates by 30–40%.
- IoT-Enabled Furnaces: Sensors monitor molten metal temperature, қысым, and chemistry, transmitting data to cloud platforms (E.Г., Siemens Opcenter). This ensures batch-to-batch consistency (variation <5%).
Sustainable Casting
- Recycled Materials: 80–90% of metal used in custom castings is recycled (AFS). Recycled aluminum cuts carbon emissions by 95% қарсы және. virgin aluminum.
- Энергия тиімділігі: Induction furnaces (30% more efficient than cupolas) and solar-powered foundries reduce energy use by 25–30%.
- Waste Reduction: Investment casting scrap is 5–15% (қарсы және. 30–50% for forging), and 3D-printed patterns eliminate pattern waste.
Жоғары сапалы қорытпалар
- Additive-Manufactured Superalloys: Scalmalloy® (Al-Mg-Sc) offers 30% higher strength than 6061, ideal for custom aerospace brackets.
- High-Entropy Alloys (Жігіт): CoCrFeMnNi HEAs have tensile strength >1,000 MPa and corrosion resistance exceeding 316L.
Custom HEA castings are being tested for next-gen gas turbines (1,200°C operation).
12. Қорытынды
Custom metal castings are a mature but continuously evolving manufacturing domain.
The right choice of process, alloy, and DFM rules delivers parts that are lighter, consolidated, and often less expensive to produce at scale than machined or fabricated alternatives.
Early collaboration between design, metallurgy and the foundry—plus prototype validation and rigorous inspection—minimizes risk and yields the best balance of cost, performance and delivery.
ЖҚС
How do I select the right casting process?
Start with required part size, complexity, surface finish and volume.
Use sand casting for large or low-volume parts, investment casting for precision complex parts, and die casting for high-volume thin-walled parts.
What tolerance can I expect from castings?
Ерекше: sand casting ±0.5–3 mm; investment ±0.1–0.5 mm; die casting ±0.05–0.2 mm. Final tolerance depends on feature size and process control.
How much does tooling cost and how many parts amortize it?
Tooling ranges widely: patterns a few hundred dollars; dies tens to hundreds of thousands.
Break-even depends on per-part variable cost—large runs amortize die costs better (10k+ parts common).
How do you reduce porosity in aluminium castings?
Use melt degassing, filtration, controlled pouring temperature, optimized gating and risering, and vacuum or squeeze casting for critical parts.
Is casting sustainable?
Yes—recycling loops for steel and aluminium are well established. Recycled aluminium requires a small fraction (~5–10%) of the energy for primary aluminium, significantly reducing embodied energy.
